Author(s)

F. A. Sawid, A. A. Issa

Abstract

The study area is a part of the Martubah plain. It extends from the east of Al Jabal al Akhdar west up to Tamimi Village, 50 km east of Darnah city, in the eastern region of Libya. Groundwater is the main source for water supply and irrigation purposes. In order to evaluate the quality of groundwater in the study area, 22 groundwater samples were collected and analyzed for various parameters. Physical and chemical parameters of the groundwater such as electrical conductivity, p^H, total dissolved solids, Na, K, Ca, Mg, Cl, HCO₃, CO₃, SO₄, and TH were determined. Chemical indexes such as the percentage of sodium, sodium ad sorption ratio, residual of sodium carbonate, permeability index, Magnesium Adsorption Ratio and Chloro-Alkaline Indices were calculated. Based on the analytical results found, groundwater in the area is generally fresh and is hard to very hard. The abundance of the major ions is as follows: Cl > HCO₃ > SO₄ > CO₃ and Na > Mg > Ca > K. The dominant hydrochemical facies of groundwater is of the Na.Mg-Cl, and Na-HCO₃ type. A Gibbs diagram shows that the groundwater samples fall from freshwater to saline water. From the sodium absorption ratio conductivity plot it was found that the groundwater samples fall in the field C₃S₁. Similarly, from a Wilcox diagram the samples fall in the field of good to permissible, permissible to doubtful and doubtful to unsuitable. Most of the groundwater samples show that the groundwater of the study area is unsuitable for drinking purposes and also not suitable for irrigation under ordinary conditions, but may be used occasionally under very special circumstances.

Keywords

Martubah plain, Al Faidiyah formation, Libya groundwater, fossiliferous limestone, physical-chemistry, magnesium adsorption ratio